Refrigerated trucks and trailers usually have aluminum floors made up of a number of extruded sections, each of which has a plurality of parallel, longitudinally-extending channels. Adjacent ones of the channels have common sidewalls, and webs which are parallel to one another and are structurally integral with opposite edges of the sidewalls. The sections are welded together to make an entire floor, which may have inside dimensions as great as 102 inches (2.6 meters) by 521/2 feet (16 meters). The aluminum floor must be insulated from the metal of the truck or trailer by which it is supported. This is usually accomplished by attaching spaced transverse wooden members to the supporting metal of the truck or trailer, and attaching the aluminum floor to the wooden members. After the assembly is complete, a froth foam is injected from a wand into the spaces which are below the floor and between the wooden members, where the floor is unsupported. Such floors leak, and must be replaced frequently, to a large extent because movement of a trailer or truck while in operation on a highway often exerts enormous forces tending to strip screws that are supposed to hold the floor to the trailer or truck and, as a consequence, stripping frequently occurs after a short time of service. Wet floors are particularly subject to this stripping.
Isocyanates and compositions that are polymerizable by condensation of the NCO groups of isocyanates with compounds having active hydrogens have been used widely since World War II to produce a broad spectrum of products ranging from coating compositions to medical appliances.